1. Field of the Invention
The present invention relates to the treatment of moving glass sheets which require proper orientation and/or alignment prior to certain processing, such as shaping glass sheets or coating a selected portion where the portion of the glass to be coated must be aligned properly in a predetermined manner with respect to a coating means. The present invention is adapted for a mass production operation, and is adpated to handle sheets moving at a faster speed than the apparatus of my earlier U.S. Pat. No. 3,701,643.
An illustrative embodiment of the present invention will describe the present invention relative to a continuous shaping of discrete glass sheets by the roll forming method. However, it will be understood that treatments other than bending may be applied to discrete glass or other rigid sheets handled according to the present invention.
2. Description of the Prior Art
U.S. Pat. No. 3,445,672 to Alex G. Dompkowski transports deformable glass sheets from a shaping station to a quenching station using a reciprocating transfer carriage provided with moving fingers that are retracted to provide clearance for a glass sheet to enter the shaping station along a roll conveyor and be engaged by shaping molds that lift the glass off the roll conveyor during shaping. The fingers extend to engage the bent glass for transfer with the carriage to the quenching station and retract to dispose the glass on to the roll conveyor at the quenching station.
U.S. Pat. No. 3,265,484 to Ritter discloses glass engaging members that move between a raised position and a lowered position. In the lowered position, the glass engaging surfaces are disposed in the plane of the path taken by a glass sheet into a shaping station in order to engage the leading edge of the glass sheet being carried along the path to correctly position the sheet relative to the mold parts just as the conveyor movement is halted or just as the glass contacts the glass engaging members or the bending cycle is timed so that the lower mold part lifts the glass sheet off the conveyor at the same time as the sheet engages the members.
U.S. Pat. No. 3,332,759 to McMaster et al discloses pivotable glass edge support devices for engaging a side edge and a lower surface of a glass sheet throughout the passage of the latter through a heating chamber.
U.S. Pat. No. 3,545,951 to Nedelec simultaneously applied glass contacting fingers that are operated together to engage each side edge as well as the leading and trailing edges of the flat sheet at a glass shaping station. All the actuating mechanisms for positioning are located internally and are not readily accessible for repair.
U.S. Pat. No. 3,701,643 to Frank represents an improvement over the previous patents by incorporating carriages provided with a pair of glass edge engagement members whose purpose is to align rather than support a moving glass sheet while the moving sheet is conveyed along an enclosed conveyor leading to a glass processing station. The carriages are reciprocated in unison between upstream and downstream positions in paths exterior to the enclosed conveyor on opposite sides of the glass sheet at the same speed as the glass in the direction of glass sheet movement while the glass engaging members move into glass engaging positions limited by stop means to provide at least two longitudinally spaced points of contact along each of the opposite longitudinal side edges of the glass sheets being aligned and oriented properly preparatory for entry into a glass processing station such as a glass shaping station.
If the glass is not in proper orientation with respect to the shaping molds, the curvatures imparted to the glass will be skewed with respect to the dimensions of the glass. If the glass is not aligned properly in a transverse direction relative to the conveyor rolls, the only kinds of curvature that can be imparted without departure from tolerance to the glass would be a cylindrical or spherical type of curve.
The Frank patent provides structure for orienting and aligning glass sheets by momentary engagement in which the actuating means for the elements that engage the glass are located in easily accessible position outside the heated enclosed atmosphere of a furnace to minimize the need for maintenance and provide easy access for maintenance when needed. The Frank patent also provides means to return the carriages to the upstream position with the glass engaging members retracted in time to receive the next glass sheet in the series.
While the glass sheet orienting and aligning apparatus of the Frank patent provided suitable operation during the early days of mass production of shaped glass sheets by the roll forming process, further improvements in the roll forming process making possible a more rapid rate of production made it necessary to apply further improvements to the sheet orienting and aligning apparatus. Also, it became necessary to treat glass sheets having more complicated outlines than those treated in the eariler days of the roll forming process. As the production speed increased and the complexity of outline of treated glass sheets became more severe, it became more difficult to retract the glass engaging members rapidly enough to insure their clearance from the remainder of the glass edge as the rear end portions of the properly oriented and aligned glass sheets passed beyond the orienting and alignment station into the roll forming station.